Many pesticides (insecticides, bactericides and fungicides) used in agriculture impart phytotoxic responses, i.e., subtle to distinct hindrances to the physiological functions of various plant species. Such pesticides may be referred to as phytotoxicants. In rendering a phytotoxic response in a plant, the efficacy of the pesticide may become compromised. For example, when the pesticide sodium fluoaluminate (common name cryolite, brand name KRYOCIDE) is sprayed onto actively growing vines, trees or vegetables, reduced metabolic activity can be observed for extended periods of time—which may exceed ten to fourteen consecutive days following the pesticide application. Although the targeted pest caterpillars may be controlled by the application of the sodium fluoaluminate, the phytotoxicity of the sodium fluoaluminate weakens the plant, predisposing it to both physical and biological stresses. Sodium fluoaluminate-induced phytoxocity is but one example, as pesticide phytotoxicity can be observed with the application of many different pesticides. For example, the fungicide chlorothalonil (brand name BRAVO) possesses broad spectrum fungicidal capabilities. However, chlorothalonil has been observed to incite physiological pesticide-induced phytotoxicity.
Other repercussions of pesticide induced phytotoxicity may occur. For example, while application of pesticides may protect the pesticide-treated plant from the target pest or pathogen, the health of the treated plants may be compromised, in many instances predisposing the plants to the next wave of pests and/or pathogens.
Furthermore, phytotoxicity limits the range of plant groups for which a phytotoxic-inducing pesticide may be registered with the U.S. Environmental Protection Agency (EPA), thereby not only limiting market size for a pesticide manufacturer but also limiting the number of pesticides available to farmers and the like to combat pests. Furthermore, phytotoxicity may oftentimes be subtle and observed indirectly, e.g., by the need to use higher rates of pesticide to achieve satisfactory pesticide performance. In other words, phytotoxicity may compromise a plant's natural resistance such that additional, supplementary assistance via additional pesticide becomes necessary. However, the degree and number of restrictions promulgated by regulatory agencies responsible for pesticide usage, e.g., the U.S. EPA and the Department of Agriculture, and the like, are increasing and moving towards lowered rates of pesticides used, less frequency of pesticide use, etc. Still further, pesticide-induced phytotoxicity has been observed to negatively impact yield and quality of the treated plants to which such phytotoxic pesticides have been applied, thus further economically affecting farmers and the like.
Attempts have been made to address pesticide induced phytotoxicity issues. However, these attempts have not been wholly satisfactory. For example, naturally-derived fungicides were once thought to possess non-phytotoxic chemistry, but resultant phytotoxicity has since been observed with these pesticides as well. For example, many such naturally-derived fungicides are derived from mushroom fungal species and are collectively known as Strobylurines. One such member, Azoxystrobin (brand names Abound, Quadris) possess broad spectrum fungicide capability, but also imparts phytotoxic reactions when sprayed, for example, onto apples.
To be successful, current and future agricultural ventures will continue to require the use of pesticides. Accordingly, there continues to be an interest in the development and use of pesticides that are effective at addressing the target pest and/or pathogen of interest, but which at least mollifies the phytotoxic responses of the pesticide treated-plant. Of particular interest are such pesticide compositions that may be effectively used at relatively low rates and which provide effective crop performance.